In a number of circumstances it is desirable to detect teeth clenching and/or teeth grinding of especially human beings, in particular with the objective of being able to detect and possibly avoid undesirable, unnecessary and/or potentially harmful teeth clenching and/or grinding. In particular it is desirable to be able to detect such teeth clenching and/grinding with the objective of being able to interfere in such a manner that the undesirable activity may be limited or even brought to an end.
Teeth clenching and/or teeth grinding may be done more or less consciously or even completely unaware, for example in the sleep, and may also cause damage or unwanted effects.
Both teeth clenching and teeth grinding may be categorized as the affliction known as bruxism; powerful jaw movements without any real function which takes the form of involuntary grinding movements of the teeth during strong clenching. This affliction may cause serious dental damages such as for example wearing of the teeth, damages to lips and the tongue, lose teeth, gingival pockets etc. Bruxism is often in addition also associated with pain in the back of the head and chronic headache.
Bruxism is normally divided into chronic and acute bruxism. Acute bruxism can happen to all and may often be observed in stress situations, for example at athletes in games or at persons that have to observe a deadline. Chronic bruxism is divided into night-time (nocturnal) and day-time (diurnal) bruxism.
Day-time bruxism is characterized by being a conscious clenching of upper and lower jaws and grinding of the teeth, although dominated by the latter. Day-time bruxism may be perceived as a bad habit. Triggering of day-time bruxism may be related to exposing a patient to stress. Day-time bruxism may be relieved relatively easy by informing the person that he/she is bruxing.
Night-time bruxism is unconscious and may normally only be perceived by the surroundings (for example relations) as an unpleasant squeaky noise. During night-time bruxism, teeth grinding is more common than teeth clenching. Night-time bruxism is often alleviated by protecting the teeth with a splint.
Using monitoring devices, it is possible to detect events related to bruxism. However, events related to bruxism may be difficult to detect because they may be similar to event related to ordinary teeth clenching. On the other hand, both day and night time bruxism typically lasts more than 2-5 seconds. This knowledge may be used to detect events directly related to bruxism and so it has been. Several monitoring devices exist to monitor events related to bruxism, for example by sensing signals from muscular activity of the jaw such as electrical signals or sound signals. In common for these devices is that they require a patient or another person to manually set up the devices such that they become adapted to the individuals, in particular such that the devices sense the signals related to jaw movements and distinguish them from other signals as given off by the individuals.
An example of a device with an automatic threshold to discriminate between normal jaw movement and muscular activity related to bruxism based on a manual setup is disclosed in WO04087258 A1.
A manual set up is far from optimal in that the sensing device may then depend on the person setting up the device. If the detected signals may be used, as for example by providing a treatment stimulus to the patient, an incorrect set up may be problematic in that a correct treatment may not be provided.